The present invention relates to a virtual storage system and control method thereof for virtualizing a plurality of storage systems logically as a single storage resource.
In the storage field, notice is being taken of “storage grids (wide area wide band shared file systems)” capable of achieving high processing performance and fault tolerance that operate in such a manner that a plurality of computing resources distributed over a network operate as a single computing resource. A method of virtualizing a plurality of storage systems logically as a single virtual storage resource is well-known as a storage grid operation method.
Technology where a logical unit of a second storage system existing outside of a first storage system is managed within the first storage system is well-known as technology for virtualizing a volume (refer to Japanese Patent Laid-open Publication No. Hei. 7-210439, Japanese Patent Laid-open Publication No. 2001-318833, or Japanese Patent Laid-open Publication No. 2004-220450).